Degradation processes of nuclear waste container materials

几十年来，加拿大一直利用核反应堆生产大量无排放电力，维持一个可行的核工业对于履行我们在《泛加拿大清洁增长和气候变化框架》中概述的减少温室气体排放的集体承诺至关重要。安全、永久地处置乏核燃料是维持加拿大和世界各地核工业生存能力的一个必要步骤。这一研究项目是与核废物管理组织合作进行的，将为开发对安全处置加拿大高放射性核废物至关重要的绩效评估模型提供所需数据库的关键部分。该项目将研究核废料容器材料腐蚀和乏燃料溶解的基本过程。将对覆铜钢废料容器材料和二氧化铀及模拟乏核燃料样品进行广泛的电化学、光谱、显微镜和表面分析实验。对镀铜钢试样，各种腐蚀过程，可能发生的条件下，在一个深地质核废料库的演变，如预期的那样，从温暖和氧化冷却和缺氧，将进行评估。其目的是确定：（i）在短期氧化期内保护底层钢免受地下水影响所需的铜腐蚀裕量，（ii）容器的整体寿命，以及（iii）容器制造问题的后果，如氢吸收和未检测到的涂层缺陷。对于燃料，将检查在燃料表面上发生的各种化学过程的速率，目的是理解和量化由辐解产生的氧化剂之间的相互作用（例如，过氧化氢）和氧化剂清除剂，例如来自辐射分解和钢容器腐蚀的氢。这项工作将由瑞典和瑞士的核废料管理当局进行监测，这两个国家也遇到类似的问题。

Canada has employed nuclear reactors to generate large amounts of non-emitting electrical power for several decades, and maintaining a viable nuclear industry will be essential to meeting our collective commitment to decreasing greenhouse gas emissions, as outlined in the Pan-Canadian Framework on Clean Growth and Climate Change. The safe, permanent disposal of spent nuclear fuel is one necessary step in maintaining the viability of the nuclear industry in Canada and around the world. This research project, performed in partnership with the Nuclear Waste Management Organization (NWMO), will furnish a critical part of the required database for the development of the performance assessment models essential to achieving the safe disposal of Canada's high level nuclear waste. This project will investigate the fundamental processes that underlie the corrosion of nuclear waste container materials and the dissolution of the spent fuel. A wide range of electrochemical, spectroscopic, microscopic and surface analytical experiments will be conducted on copper-coated steel waste container materials and on uranium dioxide and simulated spent nuclear fuel specimens. On copper-coated steel specimens, the various corrosion processes that could occur as the conditions in a deep geologic nuclear waste repository evolve, as anticipated, from warm and oxidizing to cool and anoxic, will be evaluated. The aim will be to determine; (i) the copper corrosion allowance necessary to protect the underlying steel against exposure to groundwater during the short-term oxidizing period, (ii) the overall lifetime of the containers, and (iii) the consequences of container fabrication issues, such as hydrogen absorption and the presence of undetected through-coating defects. For the fuel, the rates of the various chemical processes occurring on the fuel surface will be examined, with the objective of understanding and quantifying the interactions between oxidants produced by radiolysis (e.g., hydrogen peroxide) and oxidant scavengers, such as hydrogen from radiolysis and the corrosion of the steel vessel. The work will be monitored by nuclear waste management authorities from Sweden and Switzerland, where similar issues are encountered.